Study on the molecular mechanism of carbapenem-resistant Escherichia coli / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the molecular epidemiology and mechanism of carbapenem resistance of Escherichia coli collected from intensive care units(ICUs)of general surgery.Methods Agardilution were carried out to confirmed the drug-susceptibility,pulsed-field gel electrophoresis(PFGE)were performed to analyze the molecular epidcmiology of carbapenem-resistance isolates.Specific PCR,DNA sequencing,conjugation experiments,plasmids extraction,plasmid transformation assays and SDS-PAGE of outer membrane proteins(OMPs)were carried to confirm genotype of carbapenemase and its transmission mechanism.Results PFGE showed the isolates belonged to 10 clonotype,and all the clinical isolates were resistant to β-lactams including imipenem and meropenem,but uncertain to aminoglycosides,specific PCR and DNA sequencing revealed that all isolates encoded carbapenem-hydrolyzing enzyme gene,KPC-2.Plasmid DNA extraction and plasmid transformation assays from some isolates comfirmed that KPC-2 encoded on a 56 kb plasmid.SDS-PAGE analysis confirmed that there are alterations in OMPs of Escherichia coli.Conclusion Escherichia coli isolates with carbapenem resistance are collected from our hospital,production of KPC-2 carbapenemase mainly contributed to reduced susceptibility of carbapenem in Escherichia coli,the alterations in OMPs may as a cofactor in high-level drug-resistance in Escherichia coli.